Comparison Of The Stress Distribution At Cervical Bone Of Perfect Implant And Replace Implant

With the development and the wide application of implant technology, implant dentures have became an ideal alternative to restore dentition defect and edentulous jaws, and have been accepted as one of the major treatment concepts by dentists and patients. With the advancement of implant technology, the osseointegration has ensured stable and reliable, and the focus of implant dentistry has been on simplification of the treatment, improvement of the esthetic outcome and reduction of the treatment time. The esthetic problem has been well concerned by domestic and foreign experts nowadays. So the purpose of dental implants'design also changes from enhancing osseointegration only to considering function and esthetic effect both. Developing a natural contour and anatomically dimensioned soft-tissue margin is critical to attaining an esthetic implant restoration. The Perfect implant is designed to gain a better esthetic effect for anterior restorations, and the lowest point of its scalloped shape is at the middle of the buccal and lingual margins, while the highest point at the middle of the interproximal margins, which is the same as the enamelo-cemnetal junction. Designers believe that enhanced interproximal tissue preservation from scalloped implant designs may lead to more predictable esthetic dental implant restorations in the anterior maxilla. Whether this design can preserve the height of the interproximal bone and attain an esthetic implant restoration is still controversial. The cervical cortical bone around the neck of implant is the place where stress concentrates, so the variations of cervical shape of implant affect the stress distribution in cortical bone of implant. As a matured method, three-dimensional finite element analysis has been widely used in oral biomechanical research field. The main purpose of this study is to research the stress distribution in cervical cortical bone between Perfect implant and Replace implant,compare the stress distribution in cervical cortical of Perfect implant with different bone quantities, and whether this distinct design of Perfect implant is rational or not was analyzed, then with which bone quantities the stress distribution in cervical cortical bone is most rational was discussed. This study will provide theoretical instruction for clinical experience.With multi-software technology support, referred Yang's modulus of maxilla, the three-dimensional finite element model of maxilla anterior part of missing single central incisor was established. According to the experimental design, change the bone quantities of the three-dimensional finite element model of the maxillary anterior part, and insert Perfect implant and Replace implant respectively according to product instruction booklet.The alveolar bone, prosthesis attachment, implant and abutment material properties were considered as homogeneous, isotropic and linearly elastic in the analyses, implant 100% osseointegrated to bone. After the model had been meshed, we applied vertical and 30°buccolingual load to analysis the stress distributions of cervical cortical bone around implant.The results showed that:The stress mainly distributes at cervical cortical bone and the apical bone of implant, when vertical and inclined load was applied at all kinds of modes. Maximum stresses were located in the cortical bone. When then implants were loaded with inclined force, the stress increased respectively.With the absorption of the alveolar bone, biomechanical characteristics of the cervical cortical bone around the Perfect implant were similar to those with Replace implant. The Maximum stresses around Replace implant are greater than that of Perfect implant at the same modal.The stress distribution of the cortical bone is more reasonable when Perfect implant has been placed in where there is no bone defects than in bone defects,and the peak value of the stresses is lower.According to the results above, we can get conclusion as follow:1. The models built by CT scanning and Hyperworks software were precise, experimental results were reliable.2. In the clinical designation of the placement of Perfect implant and superstructure, not only the force of bite but also the direction of the force should both be emphasized .3. From the view of biomechanics, the scalloped contour of Perfect implant won't accelerate the speed of bone resorption at cervical alveolar ridge.4. Although Perfect implant can adjust the depth of the implant to reach the best therapeutic efficacy when bone defects, to obtain the best aesthetics effect and the long-term success rate, we should design bone grafting.